diff options
Diffstat (limited to 'clang/lib/CIR/CodeGen/CIRGenCleanup.cpp')
| -rw-r--r-- | clang/lib/CIR/CodeGen/CIRGenCleanup.cpp | 227 |
1 files changed, 220 insertions, 7 deletions
diff --git a/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp b/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp index 8700697..851328a 100644 --- a/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp +++ b/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp @@ -28,6 +28,46 @@ using namespace clang::CIRGen; // CIRGenFunction cleanup related //===----------------------------------------------------------------------===// +/// Build a unconditional branch to the lexical scope cleanup block +/// or with the labeled blocked if already solved. +/// +/// Track on scope basis, goto's we need to fix later. +cir::BrOp CIRGenFunction::emitBranchThroughCleanup(mlir::Location loc, + JumpDest dest) { + // Insert a branch: to the cleanup block (unsolved) or to the already + // materialized label. Keep track of unsolved goto's. + assert(dest.getBlock() && "assumes incoming valid dest"); + auto brOp = cir::BrOp::create(builder, loc, dest.getBlock()); + + // Calculate the innermost active normal cleanup. + EHScopeStack::stable_iterator topCleanup = + ehStack.getInnermostActiveNormalCleanup(); + + // If we're not in an active normal cleanup scope, or if the + // destination scope is within the innermost active normal cleanup + // scope, we don't need to worry about fixups. + if (topCleanup == ehStack.stable_end() || + topCleanup.encloses(dest.getScopeDepth())) { // works for invalid + // FIXME(cir): should we clear insertion point here? + return brOp; + } + + // If we can't resolve the destination cleanup scope, just add this + // to the current cleanup scope as a branch fixup. + if (!dest.getScopeDepth().isValid()) { + BranchFixup &fixup = ehStack.addBranchFixup(); + fixup.destination = dest.getBlock(); + fixup.destinationIndex = dest.getDestIndex(); + fixup.initialBranch = brOp; + fixup.optimisticBranchBlock = nullptr; + // FIXME(cir): should we clear insertion point here? + return brOp; + } + + cgm.errorNYI(loc, "emitBranchThroughCleanup: valid destination scope depth"); + return brOp; +} + /// Emits all the code to cause the given temporary to be cleaned up. void CIRGenFunction::emitCXXTemporary(const CXXTemporary *temporary, QualType tempType, Address ptr) { @@ -40,6 +80,19 @@ void CIRGenFunction::emitCXXTemporary(const CXXTemporary *temporary, void EHScopeStack::Cleanup::anchor() {} +EHScopeStack::stable_iterator +EHScopeStack::getInnermostActiveNormalCleanup() const { + stable_iterator si = getInnermostNormalCleanup(); + stable_iterator se = stable_end(); + while (si != se) { + EHCleanupScope &cleanup = llvm::cast<EHCleanupScope>(*find(si)); + if (cleanup.isActive()) + return si; + si = cleanup.getEnclosingNormalCleanup(); + } + return stable_end(); +} + /// Push an entry of the given size onto this protected-scope stack. char *EHScopeStack::allocate(size_t size) { size = llvm::alignTo(size, ScopeStackAlignment); @@ -75,14 +128,30 @@ void EHScopeStack::deallocate(size_t size) { startOfData += llvm::alignTo(size, ScopeStackAlignment); } +/// Remove any 'null' fixups on the stack. However, we can't pop more +/// fixups than the fixup depth on the innermost normal cleanup, or +/// else fixups that we try to add to that cleanup will end up in the +/// wrong place. We *could* try to shrink fixup depths, but that's +/// actually a lot of work for little benefit. +void EHScopeStack::popNullFixups() { + // We expect this to only be called when there's still an innermost + // normal cleanup; otherwise there really shouldn't be any fixups. + cgf->cgm.errorNYI("popNullFixups"); +} + void *EHScopeStack::pushCleanup(CleanupKind kind, size_t size) { char *buffer = allocate(EHCleanupScope::getSizeForCleanupSize(size)); + bool isNormalCleanup = kind & NormalCleanup; bool isEHCleanup = kind & EHCleanup; bool isLifetimeMarker = kind & LifetimeMarker; assert(!cir::MissingFeatures::innermostEHScope()); - EHCleanupScope *scope = new (buffer) EHCleanupScope(size); + EHCleanupScope *scope = new (buffer) + EHCleanupScope(size, branchFixups.size(), innermostNormalCleanup); + + if (isNormalCleanup) + innermostNormalCleanup = stable_begin(); if (isLifetimeMarker) cgf->cgm.errorNYI("push lifetime marker cleanup"); @@ -100,12 +169,30 @@ void EHScopeStack::popCleanup() { assert(isa<EHCleanupScope>(*begin())); EHCleanupScope &cleanup = cast<EHCleanupScope>(*begin()); + innermostNormalCleanup = cleanup.getEnclosingNormalCleanup(); deallocate(cleanup.getAllocatedSize()); // Destroy the cleanup. cleanup.destroy(); - assert(!cir::MissingFeatures::ehCleanupBranchFixups()); + // Check whether we can shrink the branch-fixups stack. + if (!branchFixups.empty()) { + // If we no longer have any normal cleanups, all the fixups are + // complete. + if (!hasNormalCleanups()) { + branchFixups.clear(); + } else { + // Otherwise we can still trim out unnecessary nulls. + popNullFixups(); + } + } +} + +EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) { + char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers)); + assert(!cir::MissingFeatures::innermostEHScope()); + EHCatchScope *scope = new (buffer) EHCatchScope(numHandlers); + return scope; } static void emitCleanup(CIRGenFunction &cgf, EHScopeStack::Cleanup *cleanup) { @@ -116,6 +203,18 @@ static void emitCleanup(CIRGenFunction &cgf, EHScopeStack::Cleanup *cleanup) { assert(cgf.haveInsertPoint() && "cleanup ended with no insertion point?"); } +static mlir::Block *createNormalEntry(CIRGenFunction &cgf, + EHCleanupScope &scope) { + assert(scope.isNormalCleanup()); + mlir::Block *entry = scope.getNormalBlock(); + if (!entry) { + mlir::OpBuilder::InsertionGuard guard(cgf.getBuilder()); + entry = cgf.curLexScope->getOrCreateCleanupBlock(cgf.getBuilder()); + scope.setNormalBlock(entry); + } + return entry; +} + /// Pops a cleanup block. If the block includes a normal cleanup, the /// current insertion point is threaded through the cleanup, as are /// any branch fixups on the cleanup. @@ -123,17 +222,21 @@ void CIRGenFunction::popCleanupBlock() { assert(!ehStack.empty() && "cleanup stack is empty!"); assert(isa<EHCleanupScope>(*ehStack.begin()) && "top not a cleanup!"); EHCleanupScope &scope = cast<EHCleanupScope>(*ehStack.begin()); + assert(scope.getFixupDepth() <= ehStack.getNumBranchFixups()); // Remember activation information. bool isActive = scope.isActive(); - assert(!cir::MissingFeatures::ehCleanupBranchFixups()); + // - whether there are branch fix-ups through this cleanup + unsigned fixupDepth = scope.getFixupDepth(); + bool hasFixups = ehStack.getNumBranchFixups() != fixupDepth; // - whether there's a fallthrough mlir::Block *fallthroughSource = builder.getInsertionBlock(); bool hasFallthrough = fallthroughSource != nullptr && isActive; - bool requiresNormalCleanup = scope.isNormalCleanup() && hasFallthrough; + bool requiresNormalCleanup = + scope.isNormalCleanup() && (hasFixups || hasFallthrough); // If we don't need the cleanup at all, we're done. assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); @@ -168,9 +271,119 @@ void CIRGenFunction::popCleanupBlock() { assert(!cir::MissingFeatures::ehCleanupFlags()); - ehStack.popCleanup(); - scope.markEmitted(); - emitCleanup(*this, cleanup); + // If we have a fallthrough and no other need for the cleanup, + // emit it directly. + if (hasFallthrough && !hasFixups) { + assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); + ehStack.popCleanup(); + scope.markEmitted(); + emitCleanup(*this, cleanup); + } else { + // Otherwise, the best approach is to thread everything through + // the cleanup block and then try to clean up after ourselves. + + // Force the entry block to exist. + mlir::Block *normalEntry = createNormalEntry(*this, scope); + + // I. Set up the fallthrough edge in. + mlir::OpBuilder::InsertPoint savedInactiveFallthroughIP; + + // If there's a fallthrough, we need to store the cleanup + // destination index. For fall-throughs this is always zero. + if (hasFallthrough) { + assert(!cir::MissingFeatures::ehCleanupHasPrebranchedFallthrough()); + + } else if (fallthroughSource) { + // Otherwise, save and clear the IP if we don't have fallthrough + // because the cleanup is inactive. + assert(!isActive && "source without fallthrough for active cleanup"); + savedInactiveFallthroughIP = builder.saveInsertionPoint(); + } + + // II. Emit the entry block. This implicitly branches to it if + // we have fallthrough. All the fixups and existing branches + // should already be branched to it. + builder.setInsertionPointToEnd(normalEntry); + + // intercept normal cleanup to mark SEH scope end + assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); + + // III. Figure out where we're going and build the cleanup + // epilogue. + bool hasEnclosingCleanups = + (scope.getEnclosingNormalCleanup() != ehStack.stable_end()); + + // Compute the branch-through dest if we need it: + // - if there are branch-throughs threaded through the scope + // - if fall-through is a branch-through + // - if there are fixups that will be optimistically forwarded + // to the enclosing cleanup + assert(!cir::MissingFeatures::cleanupBranchThrough()); + if (hasFixups && hasEnclosingCleanups) + cgm.errorNYI("cleanup branch-through dest"); + + mlir::Block *fallthroughDest = nullptr; + + // If there's exactly one branch-after and no other threads, + // we can route it without a switch. + // Skip for SEH, since ExitSwitch is used to generate code to indicate + // abnormal termination. (SEH: Except _leave and fall-through at + // the end, all other exits in a _try (return/goto/continue/break) + // are considered as abnormal terminations, using NormalCleanupDestSlot + // to indicate abnormal termination) + assert(!cir::MissingFeatures::cleanupBranchThrough()); + assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); + + // IV. Pop the cleanup and emit it. + scope.markEmitted(); + ehStack.popCleanup(); + assert(ehStack.hasNormalCleanups() == hasEnclosingCleanups); + + emitCleanup(*this, cleanup); + + // Append the prepared cleanup prologue from above. + assert(!cir::MissingFeatures::cleanupAppendInsts()); + + // Optimistically hope that any fixups will continue falling through. + if (fixupDepth != ehStack.getNumBranchFixups()) + cgm.errorNYI("cleanup fixup depth mismatch"); + + // V. Set up the fallthrough edge out. + + // Case 1: a fallthrough source exists but doesn't branch to the + // cleanup because the cleanup is inactive. + if (!hasFallthrough && fallthroughSource) { + // Prebranched fallthrough was forwarded earlier. + // Non-prebranched fallthrough doesn't need to be forwarded. + // Either way, all we need to do is restore the IP we cleared before. + assert(!isActive); + cgm.errorNYI("cleanup inactive fallthrough"); + + // Case 2: a fallthrough source exists and should branch to the + // cleanup, but we're not supposed to branch through to the next + // cleanup. + } else if (hasFallthrough && fallthroughDest) { + cgm.errorNYI("cleanup fallthrough destination"); + + // Case 3: a fallthrough source exists and should branch to the + // cleanup and then through to the next. + } else if (hasFallthrough) { + // Everything is already set up for this. + + // Case 4: no fallthrough source exists. + } else { + // FIXME(cir): should we clear insertion point here? + } + + // VI. Assorted cleaning. + + // Check whether we can merge NormalEntry into a single predecessor. + // This might invalidate (non-IR) pointers to NormalEntry. + // + // If it did invalidate those pointers, and normalEntry was the same + // as NormalExit, go back and patch up the fixups. + assert(!cir::MissingFeatures::simplifyCleanupEntry()); + } } /// Pops cleanup blocks until the given savepoint is reached. |